{{- $youtubeHost := "https://www.youtube.com/watch?v=" }}
{{- $url := .Get 0 }}
{{- if in $url $youtubeHost }}
  {{- $url = strings.TrimPrefix $youtubeHost $url }}
{{- end }}
<div class="video">
  <iframe src="https://www.youtube.com/embed/{{ $url }}?controls=1&rel=0" loading="lazy"></iframe>
</div>
